Recently, through one of my environmental engineering classes, I had the opportunity to tour the Edmonton Waste Management Centre. The EWMC processes all of the municipal solid waste from the city of Edmonton on site, and uses several different waste management techniques to do so. These include waste separation, recycling, composting and many others. Two of the stages that I think are particularly energy-club related are the landfill gas recovery system and the Enerkem biofuels facility.
The site of the EWMC houses Edmonton’s Clover Bar landfill, which was closed after reaching its capacity in 2009. It now serves as a source of energy for the city of Edmonton, since it produces electricity from landfill gas. All landfills produce gas as they mature and the material they house begins to degrade. The digestion of material produces landfill gas, which is made up primarily of methane and carbon dioxide, in roughly equal parts. Methane is harmful to human health, and is a potent greenhouse gas, so it is necessary to manage landfills once they reach this stage to prevent its release. However, it is also necessary to remove the landfill gases, because they pose an explosion risk if left to accumulate underground. For this reason, landfills are typically outfitted with landfill gas collection systems and, as in the case of the EWMC, a system to produce electricity from the gas. The EWMC is the only system of its kind in Alberta, and manages to satisfy about 1% of Edmonton’s yearly electricity need. This doesn’t seem like a lot on the surface, but when you think about where it’s coming from – a big, old pile of garbage – that ain’t bad. It is also expected that the landfill will continue to produce landfill gas until the year 2060, although the amount produced each year will decrease due to organic material being depleted. Considering that the landfill was only open from 1975 to 2009 (a period of 34 years), and the landfill gas recovery facility is planning to operate over a period of at least 55 years, it seems that we are getting back a lot of what we put in! (1)
In addition, Edmonton’s Waste to Biofuels Chemicals Facility is employing leading edge technology to further extract energy from waste. At the EWMC, some of the waste that cannot be recycled or composted is sent to Enerkem’s facility, which is able to produce 38 million litres of biofuels and chemicals a year from waste that would otherwise be landfilled. This waste, which is composed of things like candy wrappers and plastic bags, is turned into something called “garbage fluff,” by breaking it down into an amalgamated mixture of small pieces. It then enters the facility and, after going through Enerkem’s own process, comes out the other end as biofuel. The facility can produce either methanol or ethanol, both of which are liquid petrochemicals that can be used as fuels for internal combustion engines.1 While they are not widely used at this point, they are being used in some capacity as fuels or fuel additives, and they may produce less hydrocarbon emissions when compared to gasoline or diesel. (2)
In general, my experience at the EWMC was very enjoyable. My classmates and I lovingly compared it to an energy nerd’s version of Willy Wonka’s chocolate factory, with our guide leading us on a wonderful waste-filled adventure. But beyond it being a fun way to spend a few hours, the whole concept of the facility really got my environmental engineer senses tingling. The idea that we now extract energy from our garbage felt very futuristic to me. In fact, in one of the following classes, my professor drew a comparison to the waste fueled generator used in Back to the Future: Part II built by the infamous Doc Brown. I was also impressed at how progressive the city’s approach to waste is. While we still send a large amount of waste to landfills, the EWMC does manage to divert a pretty hefty portion of it. While it’s not perfect, it’s definitely a start. Edmonton’s facility is one of the best in the world, and people come from all over to look at the systems we have. This makes me feel pretty darn good about the city I live in.
The Edmonton Waste Management Centre holds tours for school groups or adults if you are interested in taking a look around. You can make a reservation by calling them at (780) 496-6879.
(1) City of Edmonton 2015. Edmonton Waste Management Centre [online]. Available from http://www.edmonton.ca/programs_services/garbage_waste/edmonton-waste-management-centre.aspx [cited November 1, 2015].
(2) Wiseman, R. 2014. A methanol renaissance in Canada refuels the biofuels debate. Alberta Oil Magazine, September 22, 2014 [online]. Available from http://www.albertaoilmagazine.com/2014/09/refueling-biofuels-debate/ [cited November 1, 2015].
I attended a tour of the Genesee Coal-Fired Power Plant near Warburg, Alberta on October 13, 2015. The focus of this trip was the newest generator at the plant, G3, which uses supercritical coal combustion to generate electricity. Supercritical coal combustion uses driver water at higher temperatures and pressures than subcritical combustion. This means that more power can be produced per tonne of coal, reducing overall emissions through improved efficiency (on a kW/tonne basis). G3 also uses injected granular activated carbon, atomized lime slurries (flue gas desulphurization), efficient burners and industrial filter bags (there are 11 000 filter bags at G3) to reduce Criteria Air Contaminant (CAC) emissions. These technologies are important because they put G3 and Keephills 3 (the other supercritical coal-fired power plant in Alberta) head and shoulders above other plants, in terms of emissions per tonne of coal burned. The only emissions from the power plant that are not directly addressed by technologies is carbon dioxide.
An interesting part of the coal-fired process train is the production of fly ash. Fly ash is produced by traditional coal-fired plants (not including flue gas desulphurization), and then sold to cement producers and used as a feedstock. In this way, the end products of electrical production can still be useful. One drawback of using flue gas desulphurization is that the lime in the slurry reacts with fly ash to create gypsum, which cannot be used in concrete production. Because of this, reducing air emissions creates additional waste for the electrical production process. This sucks, since the fly ash that is produced from G3 can’t be used in other industries. Lafarge is working to see if they can use the gypsum in some concrete mixes. The trend in electricity production means that desulphurization is probably going to become common place. This might become an issue for the cement industry in the next decade or so.
I was also at the UofA Energy Club Panel on the Future of Coal in Alberta on October 19, 2015. Randy Dobko, from Alberta Environment and Parks, represented the Albertan Government Ministry’s position on coal-fired electricity generation.
Mr. Dobko touched briefly on the extensive approval process that may be faced by projects in the electricity industry. They may need to apply for permits around air emissions, wastewater, groundwater, solid waste, soil and reclamation activities. This is very extensive, and requires a strong partnership between regulators and industry, as well as folks who have a solid grasp of the regulation they interact with. These regulations are focused on sustainably utilizing the environment, and providing utilities to the citizens of Alberta.
Mr. Dobko also talked about the prevalence of coal fired electricity in Alberta. Coal fired power plants provide almost 40% of the electricity in Alberta. By contrast, Ontario only operates 1 coal fired power plant, to provide during peak demand – they don’t runt the plant 24/7! There are drawbacks to all forms of energy production, but the major drawback of coal fired electrical generation is the emissions. There are mitigating technologies that are being installed at existing and new coal power plants to mitigate CAC emissions, like at G3. One emission that Mr. Dobko specifically mentioned was mercury. Coal reserves in Alberta can contain elemental mercury, which is more likely to be directly emitted. Because of this, Alberta was one of the first jurisdictions in North America to legislate the reduction of mercury emissions. Alberta has been ahead of the game on some emissions, but coal fired power plants still present a serious risk to Alberta’s overall emissions. Let’s talk about Greenhouse Gases.
Carbon dioxide is one of the most important greenhouse gases, and it is produced in large amounts at coal fired power plants. There is Carbon Capture and Storage (CCS) technology that can be operated at power plants but at present there are no major drivers to install these systems. There is currently one system in operation in Saskatchewan at a coal fired power plant. You can look at the logistics of it here: http://www.saskpower.com/our-power-future/innovating-today-to-power-tomorrow/capturing-carbon-and-the-worlds-attention/. Because of regulations that are in place to reduce greenhouse gas emissions, many of the older, less efficient coal fired power plants will most likely be closed, as it is no longer viable to operate them. This would reduce the overall emissions of CO2, but it isn’t a sustainable system for providing electricity to Albertans and protecting the environment.
Overall, it seems like coal fired electricity production needs something pushing a reduction of CO2 emissions before it can be considered environmentally friendly. The major concerns around other emissions are manageable through flue gas treatment, and other environmental impacts like thermal pollution and mining operations can be mitigated through proper operations. But greenhouse gas production still presents a major cost of coal powered electricity. As long as there is a major supply of coal in Alberta, and technologies haven’t been developed that can surpass the cost effectiveness of its electrical generation, it will keep being used. In the meantime, let’s all hope that CCS becomes more viable!